It is known, as disclosed in U.S. Pat. Nos. 4,563,582 and 4,642,464 to provide a positron emission tomography (PET) camera having a plurality of rows of scintillation crystals offset from each other on each photomultiplier tube. However, the length of crystals in the axial direction was the same as the size of the photomultiplier tube in the axial direction. Because of this length restriction on the crystals, the slice resolution of the camera was limited. In order to increase the slice resolution, a smaller crystal size in the axial direction, that is the length of the crystal, is desirable. Of course, the same configuration shown in the above named patents could be used with smaller length crystals by simultaneously using smaller size photomultiplier tubes. However, this would greatly increase the cost and complexity of the camera.
The present invention is directed to various improvements in a PET camera by increasing the axial resolution and providing more measuring slices without adding any more photomultiplier tubes.